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Grasshopper Lab
The Lubber grasshopper, Romalea microptera is a common grasshopper found in the Southeast region of the United States. It is
classified in the subphylum Uniramia and the in the class insecta. It is a typical insect with three distinct body regions, 3 pairs of legs
attached to the thorax, a single pair of antennae, mouthparts adapted for chewing and two pairs of wings. Grasshoppers, along with
katydids and crickets belong to the order orthoptera, derived from the Greek "ortho" meaning straight and "ptera" meaning wing.
External anatomy
1.
2.
Observe the three body regions all insects have: the head, thorax and abdomen.
Examine the head and locate the following parts:
Two slender antennae – Used to detect odors, touch, humidity, vibration, wind velocity and direction.
Two large, lateral Compound eyes - Each single eye can contain thousands of ommatidia. Ommatidia are like
individual lenses that sample a small part of the visual field. These lenses can be used to see shapes, color, movement and
distances.
Three, small Ocelli (simple eyes) – Located between the compound eyes. Used to detect light intensity.
Mouth parts – Labrum (upper lip), pair of jagged mandibles (Jaws) on each side of the labrum, a pair of maxillae (maxillary)
lying outside and behind the mandibles and a broad labium (lower lip). The labium and maxillae also have elongated,
segmented appendages on each side, called palps, which are used for touching, tasting and sensing temperature. Below
the labrum is a membranous tongue-like structure called the hypopharynx.
The labrum, labium and maxillae are all used for food manipulation.
The mandibles are used to capture and break up food into smaller pieces.
The hypopharynx is used to move food around in the mouth cavity.
3.
The thorax is divided into three sections: The prothorax, mesothorax and metathorax. The prothorax is the first part of the
thorax and is used as a hard shield to protect vital organs and it is where the first pair of walking legs are attached. The
mesothorax is a small segment from which arise the second pair of walking legs and it is where the leathery forewings are
attached. The last segment on the thorax is the metathorax, where the large jumping legs and the delicate forewings
attach.
Each leg is divided into the following 5 segments: Coxa: The section of a leg that is attached to the body. Trochanter: The
second segment of a leg, between the coxa and the femur. Femur: The third segment of a leg, between the trochanter and
the tibia. Tibia: The fourth segment of a leg, between the femur and the tarsus. Tarsus: The leg segment after the tibia,
often subdivided into several sections.
Grasshoppers have two pairs of wings. The forewings are leathery in appearance and are used to protect the thin,
membranous hind wings. You will need to lift the forewings to see the hind wings, which are used in flight.
4.
Examine the following structures on the abdomen:
Tympanic membranes (tympanum): Lift both pairs of wings and locate the tympanic membranes on the first abdominal
segment. These structures are used to detect sounds waves.
Locate the tiny pores or spiracles located on each side of the abdominal segments. These are openings used for respiration.
You can determine the gender of your grasshopper by looking at the end of the abdomen. Females have a tapered
abdomen that ends in a pointed egg laying structure called the ovipositor. This structure is used to dig a hole in the ground
where fertilized eggs can be deposited. Males have more of a rounded abdomen that turns upward.
5. Internal anatomy – It can be difficult to see the internal structures of the grasshopper because of the small size
and the preservative changing the colors of the tissues. You are not required to cut open the grasshopper, but if
you want to you can.
Circulatory system
In an open circulatory system, hemolymph (blood) bathes the internal tissues and organs. The tubular heart pumps
hemolymph along the dorsal blood vessel and through the lateral vessels. The hemolymph exits the lateral vessels into
open spaces and cavities of the body (hemocoel) where food and waste is exchanged in individual cells and tissues.
Because the hemolymph doesn’t transfer oxygen or carbon dioxide, it is green in color. Hemolymph collects in the ostia
(openings in the heart) and returns to the tubular heart. Valves in the ostia close when the heart contracts, preventing the
backflow.
Respiratory system
The respiratory system of a grasshopper consists of a system of air tubes (trachea) connected to holes (spiracles) that open
to the outside. The trachea branch into smaller tubules (tracheoles) which open onto or around the cells and tissues
throughout the body. Oxygen-rich air is inhaled through the first four spiracles and the carbon dioxide-rich air is exhaled
through the remaining six pair of spiracles. The process of taking in oxygen and getting rid of carbon dioxide is controlled by
the compression of air sacs and the opening and closing of spiracles.
Digestive system
The digestive tract begins with the mouth, which is located between the mandibles and the maxillae. The mouth cavity
leads to the pharynx, which a muscular structure used to push food into the esophagus. Opening into the cavity of the
pharynx and mouth are ducts that conduct digestive secretions from numerous salivary glands located ventral to the crop
and gizzard. The short tube of the esophagus leads into a food storage chamber known as the crop, which leads to the
muscular, food grinding gizzard. Food now moves to the midgut (stomach) where enzymatic digestion of food will take
place. Enzymes for digestion are secreted by gastric caeca, which are pouch-like and surround the midgut. Digestive
products now travel to the intestine, where additional nutrient absorption takes place. Digestive waste is carried from the
intestine to a small constricted colon, where excess water is reabsorbed into the body of the grasshopper. The digestive
system ends at the rectum where digestive waste can be stored until it can be expelled from the body through the anus.
Nervous system
Like most insects, the nervous system of the grasshopper, consists of an anterior brain, a longitudinal, ventral nerve cord
and specialized ganglia. The brain is located above the esophagus and is charge of movement coordination and other
sensory functions. The brain relays this information to the body of the grasshopper via the nerve cord. The many ganglia of
the grasshopper control localized functions at each specific segment.
Reproductive system
The male reproductive system consists of a pair of sperm producing testes located dorsal to the anterior half of the hindgut.
These testes open into a pair of sperm ducts, which proceed posteriorly and laterally into large sperm-storming structures
called seminal vesicles. Another duct leads from the seminal vesicles to a penis, which is inserted into the female during
copulation.
The female grasshopper has a pair of long, slender, egg-producing ovaries. Each ovary is composed of several tapering egg
tubes which produce the ova (eggs). Each ovary is joined to an oviduct leading to the vagina. Once the vagina receives
sperm from a male grasshopper, the sperm in stored in a seminal receptacle (spermatheca), until fertilization can occur in
the oviduct. The transfer of fertilized eggs to the outside is made possible through the ovipositor.
Excretory system
Malpighian tubules are long strands located at the posterior end of the stomach. These structures rid a grasshopper’s body
of undesired metabolic waste and maintain proper water concentration within the grasshopper. The excreted waste
contains nitrogen and salt and is discharged out the anus in the form of uric acid. Uric acid is the same metabolic waste
produced by birds and reptiles.
6.
Label the following head and mouthparts on the diagrams below: maxillary palps, hypopharynx, antennae, maxillary,
labium, mandible, labial palps, ocelli, labrum, compound eyes
7.
Label the following leg segments on the diagram below: tarsus, coxa, tibia, femur, trochanter
8.
Label the following parts on the diagram below: tympanum, spiracle, ovipositor, hindwing, forewing
Label the following internal structures on the diagram below: heart, ovary, colon, brain, crop, mouth, gastric caeca, stomach,
Malpighian tubes, esophagus, gizzard, rectum, nerve cord, salivary glands, intestine, anus, ganglia
1.
What does orthoptera mean?
2.
Name two other animals that belong to the same order as grasshoppers.
3.
The thorax is divided into three sections. Name the three sections.
4.
What does the prothorax do for the grasshopper?
5.
How many pairs of legs do insects have?
6.
How is the tarsus adapted for holding onto plants?
7.
How many pairs of wings do grasshoppers have?
8.
What is function of the forewing?
9.
What structure(s) do you have that are comparable to the tympanum of a grasshopper?
10. What external structure can be used to determine the gender of a grasshopper?
11. What type of circulatory system does a grasshopper have?
12. What is another name for hemolymph?
13. What makes a grasshoppers’ blood green?
14. Can you drown a grasshopper by sticking its head in the water? Explain.
15. What is uric acid?
16. Grasshoppers have internal fertilization. What structure(s) do grasshoppers have to help you know this?
17. All arthropods have jointed appendages. Name 5 jointed appendages found on a grasshopper.